Near-field communication (NFC) and radio-frequency identification (RFID) readers can identify objects via parasitically powered tags which when activated transmit the identifier (ID) of the tag. The antenna within an NFC tag is round or rectangular and magnetic induction between the antenna in the tag and an antenna in a proximate NFC reader device provides the energy for the tag to communicate its ID back to the reader device. There are many uses for NFC tags including for authentication (e.g. where the NFC tag provides an access token), for automation (e.g. where the NFC tag may initiate an action, change settings, etc.), to bootstrap other wireless connections, in commerce (e.g. in a contactless payment system), in gaming, etc.